Interior lining parts having a cover layer which forms a decorative surface are known in the automobile industry. They are used for example as instrument panels, as door linings, as column linings or even as storage compartment covers.
It is the purpose of such components to combine desired mechanical properties with optical and even haptic properties. In order to achieve this, such a component is generally composed of a carrier which determines the mechanical properties, a foam layer which determines the haptic properties and a cover layer which determines essentially the optical properties. Components are also known which dispense with the mentioned additional foam layer, i.e. the skin is connected directly to the carrier.
Furthermore, it is known to assemble cover layers from two or more skins.
However it is problematic in the case of multipart cover layers that, in the common boundary regions of the skins, foam or rear-sprayed material can emerge during rear-foaming or rear-spraying because of unsealed places and hence can reduce the quality of the surface.
A known method for foam-tight connection of skins is firstly to turn over the skins in the joint region and to sew them together in the turned-over region. The seam is then sealed in addition for the foaming process.
A further possibility of connecting skins together in a foam-tight manner is described in the publication DE 100 44 627 A1. According to the invention, two adjacent skins are connected to each other along the seam line thereof via a retaining means. In one embodiment, the retaining means is configured as a profile-like strip which clamps the adjacent skins together along the seam line. The skins connected to each other in a foam-tight manner in this way are inserted into the tool after connection to the retaining means and then are rear-foamed or rear-sprayed.
The disadvantage of these methods is that an additional method step and/or additional connection means must be used in order to connect the skins together.
The published patent specification JP 2002-052548 discloses, in the mentioned prior art, a method for the production of a component having a rear-foamed, multipart cover layer, at least two skins with angled-over end regions being inserted adjacently into a tool half of a foaming tool so that the end regions of the skins protrude into the cavity. The two end regions of the skins lie one on the other in a planar manner. The surface of the one end region is configured with a projection on the side opposite the other end region, which projection engages in a corresponding recess of the other end region. By means of this engagement, a certain sealing is achieved which is intended to prevent foam being able to emerge through a gap forming between the two end regions.
The disadvantage of this method or of this type of seal is, on the one hand, that the skins have a certain rigidity and must be fixed in their position in order to be able to retain their form and position even during the rear-foaming or rear-spraying. As a result of this, the choice of skins, the choice of pressures and the flow processes of the foam material or injection moulding material during rear-foaming and rear-spraying is significantly restricted. Furthermore, adequate sealing of such an arrangement often cannot be achieved since the contact pressure of the two end regions against each other, which is advantageous for the sealing, results solely from the position and the material properties of the skins. Furthermore, also a sufficient length of the contact region of the two end regions is required in order to ensure adequate sealing.